OneTaskBy Tim King · Updated
WebM to MP3
Audio Track Extracted at 128, 192 or 320 kbps From Recordings and Videos
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How the WebM To MP3 works
Drop in a WebM file, such as a browser voice recording, a screen capture or a downloaded clip, and download its audio as an MP3. This WebM to MP3 converter decodes the audio track with your browser and encodes it in the same tab, ignoring any video. Nothing is uploaded.
WebM to MP3: from a web container to a universal file
WebM is Google's open container, a subset of Matroska. Its audio track is Opus in almost every modern file and Vorbis in older ones; video, if present, is VP8, VP9 or AV1. Browsers produce WebM whenever a web page records sound, so online voice recorders, meeting tools and screen capture extensions all save it. MP3 is what editors, phones and podcast hosts expect, which is why WebM to MP3 is such a common need.
What changes in the conversion
- Video is dropped. Only the audio track is decoded; the MP3 holds sound alone.
- Two lossy generations. Opus or Vorbis loss is followed by MP3 loss. For speech at 128 kbps the result is indistinguishable; for music choose 192 or 320 kbps.
- Size often grows. Browser recorders save Opus at 32 to 128 kbps, so an MP3 at the same or higher rate may be larger than the WebM, especially if the WebM had no video.
- Multiple audio tracks. If a WebM holds several tracks, browsers decode the first.
Browser support for WebM audio decoding
WebM with Opus or Vorbis decodes in Chrome, Edge, Firefox, Opera and Samsung Internet. Safari decodes WebM with Opus on macOS from version 15 and on iOS from 17, but Vorbis-in-WebM and some screen recordings still fail there. If Safari cannot read a file, open the page in Chrome or Firefox.
How to read the stats
Source shows channels, decoded rate, length and the WebM size, which includes any video. Output is the MP3 bit rate and Output size estimates the MP3. A large drop from Source size to Output size usually means most of the WebM was video.
Raw Opus voice notes use Opus to MP3, Vorbis files OGG to MP3. To go the other way, audio to WebM makes compact Opus files.
FAQ
Can I convert a WebM video to MP3?
Yes. The page decodes only the audio track of the WebM and encodes that as an MP3, so screen recordings and video clips work. The video is never processed, which keeps conversion fast even for long recordings, and the MP3 contains sound only.
Why is my MP3 bigger than the WebM recording?
Browser recorders save audio as Opus, which needs far fewer bits than MP3 for the same quality. An audio-only WebM at 48 kbps becomes 128 kbps or more as MP3, so the file grows. The Output size line shows what to expect before you export.
Why does Safari say it cannot decode my WebM?
Safari supports only some WebM files: Opus audio works on recent macOS and iOS versions, but Vorbis audio and certain recorder outputs do not. Chrome, Edge and Firefox decode all common WebM audio, so switch browser if Safari refuses the file.
Is my recording uploaded anywhere?
No. The file is decoded, processed and encoded inside your browser with the Web Audio API. Nothing is sent to a server, so it works offline once the page has loaded and your audio stays private.
See also: all Audio & Video tools, Units, Images, Documents, Data & Code.
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